The present invention relates to tools for use in a wellbore, particular those wellbores drilled for water, oil, gas, other natural resources, disposal wells, and conduits for utilities. In particular, the tools disclosed provide structures that detect when a tool becomes stuck or lost (i.e., decoupled from the surface) in the wellbore and that reposition the tool within the wellbore to improve the likelihood that the tool will be recovered.
There are many types of tools that are used in wellbore, both during construction of the wellbore and after the wellbore is completed. Regardless of the type of tool, there always exists a risk that the tool will become stuck in the wellbore or lost/decoupled from the surface, regardless of whether or not the wellbore is cased or open hole. When a tool is stuck or lost downhole, subsequent operations with the wellbore are impaired, costing both time and money to remedy. Thus, it is desirable to retrieve the tool as expeditiously as possible.
Previously, tools included a fishing or latching head that allowed a fishing tool or overshot to settle and latch upon the fishing head. Once latched, the overshot and coupled tool could be retrieved with a wireline or other similar method by which it was originally conveyed into the wellbore.
New wellbore drilling and construction techniques, however, make the use of an overshot to retrieve a tool more challenging. For example, many wells now are directionally drilled and may have a very high degree of inclination. In such cases, the tool may rest on the bottom, or low side, of the wellbore as a consequence of the gravitational force acting on the tool. Since the exact disposition of the tool likely is unknown, it is often very difficult to get an overshot to land upon and latch onto a fishing head.
Previous efforts to solve this problem employed various centralizers and mechanisms. Often, however, these efforts relied upon crude measures of controlling and actuating the centralizers. For example, U.S. Pat. No. 3,087,552 discloses the use of acid soluble materials that degrade in the presence of an acid to trigger the centralizers. Such systems cause definitive deployment of the centralizers after a given period of time, but the exact time was not predictable as it is a function of the concentration of the acid, the variable properties of the materials to be dissolved, and the like. In addition, the acid had to remain in position as a “pill” or “slug” around the tool for the necessary amount of time. To do so requires that no fluid be flowing, whether around the tool when in drill pipe or casing or produced fluid during production operations. Stopping the flow of fluid around the tool potentially increases cost (particularly if a well must be shut in/killed) and risks to wellbore stability and getting the tool stuck. Further, such systems were insensitive to whether or not the centralizers actually needed to be deployed. Deployed centralizers could cause many problems, including increasing the risk of getting the tool stuck, so it is not something to be done lightly.
Thus, there is a need for a tool that reliable actuates a centralizer mechanism that would position the tool more advantageously within the wellbore in order to improve the likelihood it will be retrieved.
There further is a need for a tool that includes centralizers that can be actuated under defined conditions, regardless of whether the instruction to actuate the tool comes from the surface or is determined by the tool when certain parameters are met.